In 1995 about one million people worldwide had coronary blockages opened by dilatation. This procedure results in post--operative reclosure of the artery (restenosis) in about 30% of cases, despite insertion of a tiny mesh supporting tube (stent) at the blockage site. Recently, clinical exposures of the stented site to a very high dose rate from a "hot" iridium- 192 source mounted on a catheter tip have shown marked reduction in restenosis rates. A major disadvantage of this approach, the radiation safety problems associated with handling and inserting the source, are readily overcome with a low dose rate in vivo radioactive stent. Implant Sciences proposes to secure the advantages of both methods by testing stents employing two isotopes of greatly differing half-life, one designed to deliver a high dose rate for a short time, the other to provide the majority of the combined dose over a period of months. Using an existing ion implanter to activate stents with a 90Y/32P isotopic mixture, animal testing is proposed to evaluate the restenosis-inhibiting qualities of these devices. If they prove to be as effective as 192Ir, their thousand-times lower radioactivity should result in their acceptance as the preferred method of suppressing restenosis. PROPOSED COMMERCIAL APPLICATIONS: This research will lead to a process for ion implantation of radioisotopes into coronary stents. ISC has had interest from several stent manufacturers who plan to offer radioactive stents as soon as FDA approval is received. ISC plans to ion implant radioisotopes in their stents as a manufacturing service.